1. Technical Field
The present invention relates to: a method of controlling a liquid droplet ejection apparatus, the apparatus supplying a functional liquid droplet ejection head with a functional liquid under pressure from a functional liquid tank by pressurizing the functional liquid tank with a pressurizing pump to thereby maintain a predetermined working pressure, the apparatus also performing imaging operation by ejecting functional liquid droplets on an imaging target (or an object to which functional liquids droplets are discharged) set in an imaging region, the imaging being performed by driving the functional liquid droplet ejection head while relatively moving the functional liquid droplet ejection head and the imaging target; a liquid droplet ejection apparatus; a method of manufacturing an electro-optical device; an electro-optical device; and an electronic device.
2. Related Art
Among ink jet recording apparatuses (liquid droplet ejection apparatuses) which are known as a kind of liquid droplet ejection apparatus, there is one equipped with an ink supply apparatus (functional liquid supply apparatus) which supplies the ink jet recording head (functional liquid droplet ejection head) with ink (functional liquid) stored in an ink tank by pressurizing the ink tank (functional liquid tank) by using an air pump.
The ink supply apparatus has a sub-tank interposed between the ink tank and the ink jet recording head. The ink supplied under pressure from the ink tank is once stored in the sub-tank and is then supplied to the ink jet recording head. The sub-tank is provided with a displacement detecting means to detect the remaining amount of the ink. Depending on the amount of the ink remaining in the sub-tank, the ink is supplied from the ink tank. As a result, the pressure inside the sub-tank is kept to a certain range so that the pressure deviation (pressure surge) of the ink to be supplied to the ink jet recording head can be prevented. JP-A-2001-162834 is an example of related art.
The known ink jet recording apparatus is so constructed that, when the displacement detecting means detects a certain value, the functional liquid from the ink tank is supplied under pressure. Even during printing, the ink is supplied under pressure to the ink jet recording head once a certain value is detected by the displacement detecting means. However, if the ink is supplied under pressure to the ink jet recording during printing, there will occur pressure variations (pulsations) in the in-head passage inside the ink jet recording head by the on-off operation of the pressurizing pump. This may cause an unstable ejection of the ink droplets, resulting in a bad effect on the print quality.